Low friction stirling engines and chemical heating means



D. A. KELLY 3,508,393

LOW FRICTION STIRLING ENGINES AND CHEMIQAL HEATING MEANS April 28, 1970 1968 3 Sheets-Sheet l Filed Sept. 17,

INVENTOR. [AM/aw D. A. KELLY April 28, 1970 .LOW FRICTION STIRLING ENGINES AND CHEMICAL HEATING MEANS Filed Sept. .17, 1968 3 Sheets-Sheet 2 w a 0 Q 6 w a f l l 4/ Nu nu r L l e M nu nu w 4 L 4 HM IH/ 5 I 4 x z a G 4 4 INVENTOR. Jam-yaw ave D. A. KELLY A ril 28, 1970 LOW FRICTION STIRLING ENGINES AND CHEMICAL HEATING MEANS Filed Sept. 17, 1968 3 Sheets-Sheet 5 INVENTOR. 44% a gag FlCiGw United States Patent 3,508,393 LOW FRICTION STIRLING ENGINES AND CHEMICAL HEATING MEANS Donald A. Kelly, New York, N.Y. (506 69th Place, Maspeth, N.Y. 11378) Filed Sept. 17, 1968, Ser. No. 760,256 Int. Cl. F03g 7/06 US. Cl. 60-24 9 Claims ABSTRACT OF THE DISCLOSURE The low-friction Stirling engine is comprised of power and displacer elements which are suspended in their respective rectangular housings by large ball or roller bearings. A unique feature of the pistons is that they are square or rectangular so that the ball or roller bearings may be readily matched to the flat faces.

The engines are advocated in two versions: the first is a T, twin reciprocating block type and the second a half-rotary, high-speed type.

A chemical heating means is described which provides an economical, low air pollution, convenient heating The invention relates to improved reciprocating type Stirling engines with provision for chemical heating. Various types of Stirling engines are known, with the twin phased pistons in a common cylinder type in current limited use. This type has been extensively tested and has proved efificient in operation and is being considered for hybrid vehicular use.

Certain design deficiencies are apparent upon careful study of the arrangement which were probably necessary to provide an engine which could be economically manufactured. An unavoidable shortcoming of the design is that the hot and cold sources are not sufficiently isolated and spaced from each other and the compression ratio limited to a value not exceeding about 2.5 to 1, by relative piston displacement volumes.

In view of the described deficiencies it is advocated that the displacer unit be placed in a separate housing and the hot and cold sources be well separated and insulated from each other. It is possible to increase overall thermal eifectiveness by obtaining a gas flow loop, similar to that of the closed cycle gas turbine, without the necessity of cold area shielding by the displacer piston, as in the twin phased piston design. A conventional cooling system is utilized for both engine arrangements. A liquid cooling jacket would be secured to a maximum area of the cool side of the engine. A radiator and pump arrangement would be connected to the coolant jacket.

Square grooves are provided on the internal surfaces of the cold side of the rectangular displacer housing to provide additional cooling surface.

It will be recognized that this engine design approach is essentially returning to the original design concept of 1827 by Robert Stirling, with the heating of one end and cooling of the opposite end of the fixed volume cylinder.

When the piston or block units are separated it is necessary for compactness to dispose them at right angles to each other and provide a gear or chain drive connecting each moving block drive shaft. The major problem introduced by this configuration is that both moving.

blocks must be precisely and independently dynamically balanced, so that no excessive vibration is evident in operation. In order to minimize the mass of the counter balance required it is necessary that both moving blocks be made as light as possible with a large proportion of fiber-glass laminates being employed. The use of ball ICC bearings within both block units will reduce the operating friction level and thereby ease the amount of counter balance required.

The displacer block counter balancing crank-discs must be quite thin so that they do not occupy a large increment of the displacer volume which would decrease volumetric efficiency. Two crank discs would be employed which straddle the displacer block, one idler and one connected to the drive connection.

The chain or gear drive connecting the two moving block shafts would be enclosed within the pressurized housing so that only one pressure seal is required for the engines as in the current Stirling engine designs.

The adoption of square or rectangular reciprocating blocks makes the use of standard ball or roller bearings possible and relieves the sealing strips of excessive side pressure due to piston slap. The ball or roller bearings are not subjected to unreasonable heat levels so that their life is not adversely affected.

A controlled air gap between the moving block and the internal housing walls is highly desirable so that side loads on the sealing strips are minimized.

The sealing strips which provide the pressure sealing means for the power block are machined from filled- Teflon and are half-lapped at the ends to achieve a continuous sealing surface. It is recognized that an objection to the square piston configuration would be the pressure concentration at the corners and the attendant excessive wear of the sealing strips ends. The compensation for wear at the sealing strip ends would be accomplished by over-lapping each strip at the center and placing a small resilient silicone rubber insert in the lap joint, with a slight preload to obtain a small end pressure intO the housing corner points.

Multiple sealing strips would be required along the moving block so that an effective long-lived seal is provided in conjunction with the application of dry film lubrication on the corresponding surfaces of the internal housing walls.

It is possible that a circulating light oil lubrication system will have to be adopted in order to rovide extended operating life for the components of the engine. In order to increase the heat transfer area and rate, heating conduction rods will be placed within the hot side of the displacer volume which fit into the regenerator bores of the displacer block with clearance.

A clearance of about half the conduction rod diameter must be allowed so that the working air volume may be displaced from one side to the other, and to allow for the placing of regenerative filament within the regenerator bores.

The multiple conduction rods are uniformly spaced within the hot volume and secured to the hot side end plate which is insulated from the main housing. This arrangement provides a means of gaining effective internal heating without excessive heating of the external pressurized housing, and avoids the necessity of splitting the housing into hot and cold halves.

The top of the power housing is provided with hot and cold parts on either side of the housing so that the gas flow loop is achieved. An angular cut is provided at the hot side base of the displacer block to aid in the transfer of the hot gas into the power block volume.

A multi-disc or labyrinth type of shaft seal must be provided at the output shaft to retain the internal working pressure at a minimum friction level. The multi-disc seal would be fitted with oil wicking which is the low friction, replaceable element of the seal assembly.

The T configuration of the Stirling engine lends itself to the axial gauging of several units in a multiple pistongroup arrangement. The second type of Stirling engine would consist of a truncated rotary displacer element in place of the reciprocating displacer block, which would result in a higher speed machine. The truncated displacer rotor is fully dynamically counter balanced and functions in a similar manner to the reciprocating type with the gas shuttled back and forth from the hot to the cold side of thedisplacer cylinder.

All other components of the engine are the same as the first engine design, except that a curved adapter is required to join the power housing to the displacer cylinder. I

The truncated rotor is fitted with two end discs which carry the counter balancing weights. Multiple flow vanes are fitted to the inside faces of the discs to aid in gas flow direction.

The chemical heating arrangement provided consists of utilizing the heat value of certain exothermic chemicals in a reaction tank secured to the hot side of the engine. The chemical and water supply tanks would be mounted above the reaction tank to supply the ingredients necessary for the heating reaction. A dump tank would be located under the reaction tank to receive the expended chemical solution.

For some engine applications conventional heating means such as propane or oil burners will be required for higher heating levels and improved performance.

It is expected that the engine will be capable of operating at pressure levels up to one hundred atmospheres so that a high power-to-weight ratio output will be obtained. A side benefit to the application of square working components is that larger effective piston areas are obtained for a given housing area or stated another way the corner areas of a circle inscribed within a square are not lost working areas.

It is an object of the invention to provide an advanced Stirling engine which operates at a minimum friction level by the wide application of anti-friction bearings.

It is an object of the invention to achieve an engine which operates'at a high thermal efficiency !by the placement and arrangement of the operating components.

It is an object ofthe invention to utilize the advantages of square or rectangular working blocks in place of conventional pistons.

It is an object of the invention to provide an engine design which is compact and inexpensive to manufacture.

It is an object of the invention to utilize a low-cost chemical heating means for economical engine operation.

The above objects and other aims will be apparent from the detailed description to follow when taken in conjunction with the appended drawings.

It should be understood that variations may be made in the detail design without departing from the spirit and scope of the invention.

Referring to the drawings:

FIGURE 1is a top sectional view thru a T version engine.

FIGURE 2 is an elevational section thru a T version engine.

FIGURE 3 is a top sectional view thru a half-rotary version engine.

FIGURE 4 is an elevational section thru a half-rotary version engine.

FIGURE 5 is a side elevational section thru a T version engine.

FIGURE 6 is a pictorial view of the power block and connecting rod.

Referring to the drawing in detail:

The power stage housing 1 is built up of aluminum plates made up in rectangular form and sealed pressure tight, with the inside surfaces 1a made flat and smooth to minimize wear on the sealing strips. The machine screws 1b join the plates together. The power block 2 is built up in square form of aluminum plate and is fitted with ten ball or roller bearings .3. The bearings 3 are supported by six shafts 4, with the bearings 3 revolving in 4 the slots 5. The machine screws 6 join the aluminum plates of the power block 2 together.

The power block is provided with sealing grooves 7 into which the sealing strips 8 are closely fitted. The sealing strips are half-lapped at the ends so that continuous perimeter sealing is maintained. 1

The wrist pin 9 connects the power block 2 with the connecting rod 10. The crank shaft assembly 11 is built up of a shaft and two counterbalance discs 12 with the crank pin 13 connecting the two counter-balance discs 12. The crank end of the connecting rod 10 is connected to the crank pin 13.

One of the counter balance discs is fitted with a center stud 14 which is supported by the bearing 15. The output end of the crankshaft assembly 11 is supported by the main bearings 16 and sealed by the multi-disc seal 17.

The displacer stage housing 18, constructed in rectangular form of aluminum plates and sealed pressure tight. The displacer stage housing 18 is mounted across the power stage housing 1 to form a T form. The displacer stage housing 18 is secured to the power stage housing 1 and baseplate 19, with the machine screws 20.

The hot transfer ports 21 and cold transfer ports 22 are located at opposite sides of the power stage housing 1 and provides the gas flow passage between the two stages. The two bores 21 and 22 are bored through the base plate of the displacer stage housing 1 and the base plate 19.

The hot side plate 23 is insulated from the displacer stage housing 18 by the gasket 24. Heat conduction copper rods 25 are secured to the hot side plate 23 to provide complete internal heating.

The displacer block 26 is built up of aluminum sheet and fiberglass and fitted with ball or roller bearings 3. The bearings are supported by six shafts 27, with the bearings 3 revolving in the slots 28. The machine screws 6 join the plates of the displacer block 26 together.

Multiple regenerator bores 29 are located through the displacer stage block 26 and must match the location of the heating conduction copper rods 25, which fit into them 1n operation.

The regenerator bores 29 should be a minimum of one and. one-half times the diameter of the conduction rods 25, so that proper operation is obtained, and to allow for the placement of the regenerative filament 30 necessary for heat storage between the phases of the cycle.

Two vertical drive slots 31 are located at mid-length of the displacer block 26 sides, which pick up the drive ball bearing 32 of the crank discs 33.

One crank disc 33 is secured to the displacer drive shaft 34 and supported by the two ball bearings 35. The other idler crank disc 33 is fitted with a center stud 36 which is supported by the bearing 37. A chain sprocket 38 is secured to the displacer drive shaft 34 between the two ball bearings 35. An identical sprocket 38 is also secured to the crank shaft assembly 11 With the chain 39 providing the interconnecting drive between the two stages.

A cover plate assembly 40 is secured and sealed to both the power stage housing 1 and the displacer stage housing 18 and seals the sprockets and chain drive. The cover plate assembly 40 provides bearing support for both shafts 11 and 34, through the bearings 16 and 35 fitted into it.

The multi-disc seal 17 is made up of stator discs 17:: and rotor discs 17b and spacers 170. Oil wicking 17a is fitted around the rotor discs to provide the sealing means. The disc and spacer assembly is placed within the housing 17s and is secured in place to the cover plate assembly 40.

In the half-rotary version of the basic engine, a displacer cylinder 41 replaces the displacer stage housing 18. The truncated rotor 42 with two end discs 43 secured, form the displacer stage element. Counterweights 43a are secured to the inside face of each end disc 43, so that the displacer rotor is dynamically counterbalanced.

Multiple flow vanes 44 are fitted to the inside faces of the end discs 43, to aid in gas flow direction. The vanes may be fitted with pivots 45, so that the vanes may be adjusted or oscillated during rotation.

The rotor shaft 46 is mounted in the same manner as in the two block design, with the chain sprocket 38 secured to it. The same cover plate assembly 40 is mounted to the housings.

A curved adapter plate 47 must replace the base plate 19 so that the power stage housing 1 may be closely fitted to the displacer cylinder 41. The hot transfer ports 48 and cold transfer ports 49 would be disposed at an angle nearly tangent to the internal bore of the displacer cylinder 41, to provide a natural ingoing and outgoing gas flow. The truncated rotor 42 is provided with regenerator bores 70 and metallic regenerator filament 71.

The cooling system for the engine consists of a liquid coolant jacket 50, secured to the cold engine side with all surfaces in contact with the coolant jacket surfaces. Inlet tubing 51 and outlet tubing 52, connected to the jacket 50 circulates the coolant to the radiator 53.

The coolant pump 54 provides circulating power for the coolant through the cooling system. The extended cooling area grooves 55 provide additional cooling surface on the interior surfaces of the housing.

The heating system for the engine consists of a closed reaction tank 56, which contains multiple, vertical conduction plates 57, to aid in conducting heat from the chemical reaction to the hot engine surfaces. The reaction tank may be a wrap-around type, where four or five surfaces are in contact with the engine. A chemical supply tank 58, and a liquid supply tank 59, are located above the reaction tank 56 and are supported by the frame 60. Transfer tubes 61 and shut off valves 62 are located between the supply tanks 58, 59 and the reaction tank 56.

A dump tank 63 is located below the reaction tank and is supported by the frame 64. A transfer pipe 65 and shut off valve 66, receive and control the flow of the spent solution from the reaction tank. A drain pipe 67 and valve 68 are located under the dump tank 63, to drain the tank 63.

A conventional oil or propane burner 69 may be provided to heat the engine if required for higher engine performance.

What is claimed is:

1. A pressurized gas reciprocating Stirling cycle engine comprising a rectangular power stage housing, a square power block fitted with multiple ball bearings in rolling association with the internal surfaces of the said rectangular power stage housing, rectangular sealing strips disposed within corresponding grooves within the said square power block, a wrist pin secured inside of the said square power block, a connecting rod pivoting on the said wrist pin, a crank shaft disposed at one end of the said rectangular power stage housing, bearing means for the said crankshaft, sealing means associated with the said crankshaft, a crank pin secured to the said crankshaft in rolling association with the said connecting rod, hot and cold ports disposed within the end of the said rectangular power stage housing, a rectangular displacer stage housing disposed at one end of the rectangular power stage housing in the form of a capital letter T, a squarish displacer block fitted with multiple ball bearings in rolling associated with the internal surfaces of the said rectangular displacer stage housing, multiple uniformly disposed regenerator bores within the said squarish displacer block, regenerative metallic filament uniformly disposed within the said regenerator bores, multiple uniformly disposed conduction rods secured to the hot end of the said rectangular displacer stage housing in close association with the said multiple uniformly disposed regenerator bores, two laterally disposed slots midway within the squarish displacer block, two crank bearings secured to two crank discs in rolling association with the said laterally disposed slots, an output shaft and bearing means secured to one of the said crank discs, a pivot and bearing means secured to one of the said crank discs, two chain sprockets secured to the said output shaft and the said crankshaft, a drive chain connected to the said two chain sprockets, a pressure tight cover plate disposed over the said two chain sprockets and drive chain.

2. A pressurized gas reciprocating Stirling cycle engine according to claim 1, including a chemical heating means comprising a chemical reaction tank, multiple heat conducting plates, a chemical supply tank disposed above the said chemical reaction tank, a liquid supply tank disposed above the said chemical reaction tank, transfer tubes and shut off valves disposed between the said chemical and liquid supply tanks and the said chemical reaction tank, a dump tank disposed under the said chemical reaction tank, a drain tube and valve disposed between the said chemical reaction tank and the said dump tank, a drain valve disposed at the bottom of the said dump tank, exothermic chemicals used in conjunction with the said chemical reaction tank.

3. A pressurized gas reciprocating Stirling cycle engine according to claim 1 wherein the said sealing means associated with the said crankshaft is comprised of multiple rotor discs equally spaced and secured to the said crankshaft, multiple stator discs interspaced with the said multiple rotor discs equally spaced and secured to a stationary shell aflixed to the said rectangular power stage housing, flexible oil wick disposed at the periphery of each said multiple rotor discs, light viscosity oil impregnating the said oil wick.

4. A pressurized gas reciprocating Stirling cycle engine according to claim 1 wherein roller bearings are used in place of the said ball bearings, a dry film lubrication is applied to the internal surfaces of the said rectangular power stage housing, and a light oil circulation system is applied to the internal surfaces of the said rectangular power stage housing.

5. A pressurized gas reciprocating Stirling cycle engine according to claim 1 wherein a conventional burner supplies heat for the engine, oil or gas fuel for the operation of the said conventional burner, a cooling system comprising a liquid jacket, connecting tubing from said liquid jacket, a heat transfer radiator connected to said connecting tubing, pumping means within said cooling system, suitable liquid coolant for the said cooling system.

6. A pressurized gas reciprocating Stirling cycle engine comprising a rectangular power stage housing, a square power block fitted with multiple roller bearings in rolling association with the internal surfaces of the said rectangular power stage housing, rectangular sealing strips disposed within corresponding grooves within the said square power block, a wrist pin secured inside of the said square power block, a connecting rod pivoting on the said wrist pin, a crankshaft disposed at one end of the said rectangular power stage housing, bearing means for the said crankshaft, sealing means associated with the said crankshaft, a crank pin secured to the said crank shaft in rolling association with the said connecting rod, hot and cold ports disposed within the end of the said rectangular power stage housing, a displacer stage cylinder disposed at the port end of the said rectangular power stage housing, a truncated cylindrical rotor disposed concentrically within the said displacer stage cylinder, a rotor shaft secured through the said truncated cylindrical rotor, two end discs disposed at either side of the said truncated cylindrical rotor, counter weights secured to the unsupported inside portions of the said two end discs, multiple flow vanes peripherally disposed around the inside faces of the said two end discs, adjustment means for the said multiple flow vanes.

7. A pressurized gas reciprocating Stirling cycle engine according to claim 6, wherein the said multiple flow vanes are provided with pivots and oscillating means.

8. A pressurized gas reciprocating Stirling cycle engine according to claim 6, wherein the said hot and cold ports are disposed at angles nearly tangent to the inside surfaces of the said displacer stage cylinder.

7 8 9. A pressurized gas reciprocating Stirling cycle engine 2,475,770 7/ 1949 Wijsman 60 -24 according to claim 6 wherein the said truncated cylindrical 2,789,415 4/ 1957 Motsinger 6024 rotor contains multiple diametrical regenerator bores the 3,147,600 9/ 1964- Malaker et a1 60--24 XR said multiple diametrical regenerator bores containing uniformly disposed metallic filament.

References Cited UNITED STATES PATENTS 1,128,860 2/1915 Engel et a1. 60-24 2,044,330 6/1936 Richter 6024 XR 10 U.S. C1. X.R. 

